future rice production in madagascar where and how much ?
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Future rice productionin Madagascar
Where and how much ?
Robert Hijmans & Alice Laborte
International Rice Research Institute
Background
• Madagascar’s population is largely rural, very poor & dependent on agriculture
• Rice is the main crop and staple food & cassava is also important.
• Madagascar is a net rice importer. Government aims to double rice production between 2005 and 2012
• Production (kg) = Area (ha) * Yield (kg / ha)
• Area expansion (habitat loss?) or intensification (pollution?)
2 modeling approaches
• Regression: Where would area expansion take place?
• Simulation: Climate change effect on yield
Regression model
Rice area as function of:
a) biophysical factors
b) socioeconomic factors
c) biophysical + socioeconomic factors
d) bio. + soc. factors (2 regions: W, CE)
Variable Unit 1 2 3
Intercept 17.039** 0.364** 12.469**
Elevation km -0.679** -0.490**
Slope deg -0.055** -0.063**
Slope – focal mean deg -0.147** -0.114**
Sqr(Slope) deg2 0.005** 0.005**
Rainfall m 0.757** 0.677**
Mean temperature °C -1.255** -0.851**
Sqr(Temperature) °C2 0.022** 0.013**
Distance to roads km -0.121** -0.114**
Distance to towns km -0.094** -0.091**
Population density person km-2 0.009** 0.002**
Population density – change
% -0.002**
Income million francs 1.458** 2.165**
D2 0.09 0.11 0.16
Area under ROC 0.70 0.73 0.76
AIC 26,930 26,382 24,928**Significant at 0%, * 5%
a b c
Model
**Significant at 0%, *1%
Model d
Variable Unit AS, MA, TL AV, FI, TM
Intercept 8.722** -14.417**
Elevation km -3.304** -4.306**
Sqr(Elevation) 2.007** 1.295**
Slope deg -0.071**
Slope – focal mean deg -0.125** -0.150**
Sqr(Slope) deg2 0.003** 0.005**
Flow accumulation – focal mean -0.012**
Rainfall m 1.817**
Mean temperature °C -0.328** 2.393**
Sqr(Temperature) °C2 -0.075**
Distance to roads km -0.150** -0.125**
Distance to towns km -0.097** -0.107**
Population density person km-2 0.009** 0.002**
Population density – change % -0.035** 0.011**
Income million francs 5.139**
D2 0.18 0.20
Area under ROC 0.78 0.79
Center-East West
< 2.5 2.5 - 5 5 - 7.5 7.5 - 10 > 10
Current conditions2080A2a, Hadcm3
November planting of IR64, irrigated
Implications?
Part of the climate change effects on yield potential can be easily dealt with (length of growing season)
Current yields are very low; Need for intensification; opportunities are not much affected.
Water supply, double cropping?
Resilience to extreme events (flooding, drought)
More rice in the central highlands? Or diversification to high value crops?
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